Looks like a nice score.
Youre going to have a hell of a time cramming in those newer engines. It can be done, but be prepared for a lot of time, money, and effort. Its a quite a project. I would start with basic stuff to get it back on the road and running (and stopping) in perfect shape. Then once youve had it awhile, you can make the choice if you think all that work is worth it.
Id clean it up and enjoy it for awhile before it gets stuck in the garage for the months of swap time.